Ecologists are researching the reefs around the Hunga Tonga-Hunga Ha'apai volcano to see how the biodiversity might fare.
When the volcano erupted in late 2014, it temporarily changed water temperatures by up to five degrees celsius, and dumped masses of ash into the sea.
The remaining crater became the newest land mass on Earth.
Scientists went there four years later, to see if surrounding coral and fish populations had survived.
Reef ecologist Dr Patrick Smallhorn-West spoke to RNZ.
